I would remove the lamp and the cabinet over the toilet. Paint the wall a solid color. Add a coordinating shower curtain. Possibly paint the cabinet under the sink and change the hardware and possibly paint the trim of the window black to match the tile on the floor.

I agree with ilikefriday! How about a new toilet? You didn't say what the budget is. You can get remanent granite which can be affordable for the current vanity. Home Depot sells cabinets with stone top units which are afordable too. . Sinks don't have to cost a ton!

If you are working with what you have - use the colors that you see

white and black, walls white match the wall tile, paint the vanity cabinet black, find a graphic black & white shower curtain, use black towels, find a vertical piece of art that has black, white and a bit of brown (to tie in the window frame color)